Electromagnetic variable-speed mechanism.



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PATBNTED SEPT. 17, 1907.

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A. GHURCHWARD. ELECTROMAGNETIC VARIABLE SPEED MECHANISM. APPLICATIONFILED Dnc zo. 1902 WITNESES.

7. o 9 l 7s l mh D.. E S D E T N E T A P A. CHURGHWARD. BLECTROMAGNETICVARIABLE SPEED MEGHANISM.

APPLICATION FILED DEG. 20, 1902.

2 SHEETS-SHEET 2.

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INVENTOR UNITED STATES PATENT OEETGE.

ALEXANDER.CHURCI-IWARD, OF NEW YORK, N. Y., ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OI" NEW YORK.

E LE CTROMAGNETIC VAIR/IAB LE-S-PEED ME CHANISM.

Specification of Letters Patent.

Patented Sept. 17, 1907.

' Application filed December 20, 1902. Serial No. 135,950. f

transmission mechanism and especially to that class of "variablelspeedtransmitting devices which utilize a plurality ofelectro-magnetically-actuated clutches for obtaining a wide range ofspeed variation from a source of power running at substantially aconstant rate of speed or at a speed variable between narrow limits.

It is especially applicable to the driving of printing I "presses,machine tools, motor vehicles, andthe like,

- which require a great range of speed variation.

l Heretofore it has been proposed to construct electromagneticvariable-speed gearing comprising two disk electro-magnets (or a doublefaced electro-magnet) fixed on a shaft with corresponding disk armaturesrigidly attached to transmitting wheels of different diameters looselymounted on said shaft. Such constructions have not proved satisfactoryowing to the fact that in changing speed by denergizing oneelectro-magnet and then energizing another the apparatus is subjected toasevere shock, and if the second magnet is ener- V j gized before theother has been denergized there is a Atendency for the device to lockand stop. If spur gears are used as the transmitting means under thesecongears. Furthermore in such devices it is not possible ;'magneticengagement owing to the action of the residual magnetism in 'theelectro-magnetic clutch members.

"- i The object of my invention is to preventsudden jar yto theapparatus or locking of the members of the energized clutches whilepassing from the combination of gears controlled by one electro-magnetto that cptrolled by another, and at the same time to obtain a widerange of speed variation from a source of power running at substantiallya constant late of speed or a 'speed variable within narrow limits. i

My invention consists of means for controlling a plurality ofelectro-magnetic yclutches in a variable-speed mechanism so that auniform acceleration through a wide'range of speeds is obtained in thedevice to which said mechanism is applied from a source of power whichis adapted to vary in speed through a comparatively small range.

My invention further consists of means for inserting lditions there is atendency to strip the teeth from said l a resistance in series With-theactuating coils of two clutches which are simultaneously energized whilechanging from the combination of gears or transmitting wheels operatedby one clutch to that operated by the next successive clutch in order toreduce the effective magnetic attraction of said clutches and allow acertain amount of slip between the members of the clutches therebypreventing any shock or jar to the apparatus and eliminating alltendency to lock the mechanism at` the time oftransition. v ,i l Myinvention further consists of meansfor varying the speed of the sourceof power between certain limits while the variable-speed mechanism isoperating with one electro-magnet energized whereby the speed of saidmechanism is varied gradually between thehighest speed obtainable withone combination of gearsto` the lowest obtainable with the nextsuccessivelcomhi. nation of gears. When an electric motor is 'as the 70source of power this speed variation is preferably'fob-f tained byvarying the vfield strength of said motor. i

In the accompanying drawings which illustrate the 'i l preferredembodiment of my invention, Figure Irepresents diagrammatically a systemofpcontrol for the electro-magnetic variable-speed mechanism; Fig. 2isafront elevation of my variable-speed mechanism in its preferred form,Fig. 3 is a plan view partly in section of the same; Fig. 4 is adiagrammatic representation of one way in which the coils oftheelectro-magnetic clutches shown in Fig. 3 may be connected to thecontrolling de vices; and Fig. 5 is an end view of the main shaft ofsaid variable-speed device showing the manner in which the collectorrings on said shaft are connected to the coils of the clutch members. Y

Referring now to Fig. l, C represents a controller for controlling theoperation of the clutches which are adapted to connect the motor M toits work by means of the variable-speed mechanism to be hereinafterdescribed. The actuating coils of said clutches .are 90 represented byA, B, C and D. The several positions of the controller C are indicatedbythe vertical dotted lines l to 23 inclusive.l The contact-fingers ofsaid controller are designated by a, b, c, d, t2, e, f and 1 to 1linclusive, while the contact segments carried by 95 lthe rotatable ormovable member of the controller which are in use when the coil D isthrown into operation are indicated by d2, t, f 2, ld to 4d inclusive,and 5 to l1 inclusive. The contact segments t, 5 and 9 are in use in allthe remaining operative positions of the controller. When the coil C isin operation theadditional contact segments used are c2, e2 and 1c to 4inclusive. When the coil B is in operation' the additional contactsegments used are b2, f3 and 1b to 41 additional segments in use are a,a3 and 1n to 4 inclusive.

The resistance 16 is adapted to be connected in circuit with thearmature 13 of the motor M and is cut out of said circuit step-by-stepin starting the motor. The resistance 15 is adapted to be inserted orcut out stepby-step in circuit with the motor field coil 14 therebyvarying the speed of said motor between certain predetermined narrowlimits during the time that each of said clutch coils is connected incircuit. The resistances 17 and 18 are adapted to be inserted in theclutch coil circuits during the transition positions of the controllerin order to weaken the effective pull of the clutch magnets on theirrespective armatures.

In Figs. 2 and 3 I have shown the preferred form of my electromagneticvariablespeed mechanism as adapted to be applied to the running of amachine tool. Mounted upon the base plate 25 are the standards 2G, 27and 28 which support bearings in which the main shaft 29 is adapted torotate. Keyed to theshaft 29 are the magnetic clutch members 55 and 56which carry the actuating coils C, D and A, B respectively. The saidcoils A, B, C and D are held in place in annular grooves in therespective faces of said clutch members by means of the metallic bushingor packing 58, a layer of insulating material 57 being inserted in saidgroove between the coil and the said metallic packing. The said coilsare arranged so as to form a double magnet the opposing faces of whichare adapted to engage movable armature disks which are loosely mountedon the shaft 29. The armature disk is mounted on the sleeve 51 andcarries the gear 32. The said armature and gear are adapted to be movedlongitudinally on the shaft 29- when the coil A is energized andnormally rotate freely on said shaft. The armature 49 which is adaptedto be moved longitudinally on the shaft 29 by means of the magnet coil Bis mounted on the sleeve 48 and carries the gear wheel 34. The armaturedisk 47 which is adapted to be moved longitudinally on the shaft 29 bymeans of the magnet coil C is mounted on the rotatable sleeve 46 andcarries the pinion 36. The armature 45 movable longitudinally on theshaft 29 by the magnet coil D is mounted on the sleeve 44 Which is ableto rotate freely on said shaft and carries the pinion 38. Passingthrough the magnetic clutch members 55 and 56 are the rods 60 and 61respectively which are slightly longer than the distance between theopposite faces of said magnets. The rod 6] is adapted to prevent thearmatures 50 and 49 from simultaneously contacting with the oppositefaces of the magnetic clutch member 56 when the coils A and B areenergized at the same time. After the coil A has been energized and thearmature disk 50 attracted to the face of the magnet 56 there is atendency for the 'armature disk 50 t stick to said face, due to theresidual magnetization even after the coil A has been deenergized. Whenthe coil B is energized and the armature disk 49 is moved to contactwith the face of the magnet 56 the rod or rods 61 operate to force thearmature disk 50 away from the opposite face of said magnet 56. Alsomounted on the base plate 25 are the standards or supports 39, 40 and 41which carry bearings or trunnions in which the countershaft 3G isadapted to rotate. Keyed orotherwise fastened to the shaft 30 are thepinions and gears 31, 33, 35 and 37 which are adapted to coact with thegear wheels and pinions 32, 34, 36 and 38 respectively. The saidcountershaft 30 also carries the pulley 42 which is adapted to beconnected in any desirable manner with the source of power, such as themotor M, shown diagrammatically in Fig. 1. 'lhe power at the differentspeeds obtainable in the variable-speed mechanism may be taken from theshaft 29 through the pinion 52 or by means of the pulley 43 each ofwhich is keyed or otherwise fastened to said shaft. Mounted on the endof the said shaft 29 and insulated therefrom are collector rings a, b,c, d/ne and f which are connected to the coils A, B, C and D in such amanner as is shown in Fig. 4. One terminal of each of the coils A, B, Cand D is `connected respectively to the collector rings a b, c and dthrough the connecting strips 21, 22, 23 and 24. The leads from saidcoil terminals pass through the hollow shaft 29 and are connected at theend of said shaft by means of binding posts or connectors t0 theconnecting strips 21, 22, 23 and 24. The other terminals of coils A andC are connected together and are also connected to the collector ringfthrough the connecting strip 20. The other terminals of the coils B andD are connected together and are also connected to the collector ring ethrough the connecting strip 19. The brushes a, b4, c, d, e* and f4 areadapted to contact with the collector or contact rings a, b, c', d, eand f respectively and are connected to the proper con- `tact-fingers inthe controller C as shown in Fig. 1.

l In the operation of this device the switch S in the mains T and T2which lead to the source of current supply is first closed. ln the firstposition of the controller the coil D is connected in circuit and themotor M is started. While the controller C is moving through its firstfour operative positions, called the starting positions and indicated bythe vertical dotted lines l, 2, 3 and 4, the motor M is increased inspeed as the resistance 16,is cut out of circuit step-by-step when thecontact segments 6 to 11 inclusive engage the fingers 6 to 11 inclusiverespectively. When in the fourth position of the controller C, which isreally the first running position, the motor M is running at the maximumspeed obtainable with full field strength, the shunt around the entireresistance 15 being maintained by the engagement of the contact-finger 4with the contact segment 4d. As the controller is moved forward throughthe fth, sixth, seventh and eighth positionsI the resistance 15 isinserted step-by-step in the field circuit of the lnotor M therebyreducing the field strength of said motor and gradually increasing thespeed of the motor and increasing the speed of the shaft 29 from thelowest speed obtainable by means of the combination of gears 37 and 38when the coil D is energized to the lowest speed, or just alittle belowthe lowest speed, obtainable by means of the combination of gears 35 and36 when the coil C is energized and the motor is running at its lowestspeed. When in the eighth position of the controller the entireresistance 15 is inserted in series with the field coil 14 of the motorM. In passing from the eighth position to the ninth position theresistances 17 and 18 are connected in series with the magnet coils andD when the contact-fingers c and d are in engagelment simultaneouslywith the Contact segments ci' and d2, then immediately thereafter thecircuit of the magnet coil D is broken, the resistances 17 and 18 cutout of circuit leaving the magnet coii C connected in circuit. As thecontroller is moved into the ninth position a shunt is thrown aroundtheresistance 15 by the engagement of the contact finger 4 with theContact segment 4c thereby causing a sudden reduction in the speed ofthe motor M to that corresponding to thefourth position of thecontroller. The resistances 17 and 18 are inserted in the circuits ofthe magnet coils C and D during transition period so as to weaken theeffective magnetic pull of the said magnet coils on the armatures 45 and47, so that a slip will take place between the said armatures and themagnet 55 such a slip being necessary since 4the gears 35 and 37 whichcoperate with the pinions 36 and 38 are of different sizes.

.While any one 0f the coils A, B, C and D is energized the armatureswhich are 'operated by the other of said coils are rotated freely on theshaft 29 at different speeds by means of the gear wheels and pinionscarried by the power shaft 30.

The circuit through the motor and the magnet coil D whcnthe motorcontroller C is thrown into its first operative position is as follows:starting from the main T through the switch S, blow-out coil 12,contact-finger'5,

to contact segment 5. where it divides, one branch of said circuitfollowing the course through the contact segment 6', contact-fingers 6and 10, contact segments 10 and 11, contact-finger 11, entire resistance1 6, armature 13 ofthe motor M to the negative main T2, another branchof said circuit following the course from the contact segment 5 to thecontact segment 4d, contact-finger 4, field 14 of the motor M to thenegative main, and a third branch of said circuit follows the paththrough the contact segment f-, contact-finger f, collector ring f coilD, collector ring d, contact-finger d, contact segments dand L.contact-finger t2 to the negative main Tf through the switch S. Thecircuit through the contact-finger 4 acts as a slnmt around theresistance 15 in the motor field circuit, one end of said resistance 15being connected permanently with the field 14 and the other end of saidresistance being connected with the positive main through the conductor15. The circuit through the contact-finger f as above described inaddition to ii s function of connecting the coil D in the energizingcircuit operates as a shunt around the resistance 18 which ispermanently connected between the positive main T and the conductorleading to the contact ring f at the point 18.

The circuits through the motor and the magnet coil AD when thecontroller is in its eighth position may be traced as follows: from thepositive main T through the switch S, blow-out coil 12, contact-finger5, contact segments 5 and fl. contact-finger f, collector ring f. coilD, collector' ring d, contact-finger d, Contact segments d2 and tandcontact-finger t' to the negative main T2,the said circuit branching atthe-contact-finger 5 and following the course through the contactsegment 9 contact-finger 9, armature 13`of thermotor M to the negativemain T2. The shunt fieid'coil 14 is now connected directly across themains through the conductor' 15 and the whole of the resistance 15.

In the transition position midway between the eighth and ninth positionsof the controller C, the motor circuit may be traced as follows: fromthe positive main '1" throughthe switch S, blow-out coil 12,contact-finger 5, contact segments 5 and 9 contact-finger 9, armaturc 13of the motor M to the negative main T2. The field coil 14 is connectedacross the mains in series with the whole of the resistance 15 throughthe conductor 15 as in the eighth position of the controller abovedescribed. Since in this transition position of the controller thecontact segments c'l and d2 overlap so as to contact with thecontact-fingers c and d simultaneously the circuits through the magnetcoils C and D may be traced as follows: from the positive main T throughthe conductor 15, resistances 17 and 18 in parallel, connections 17 and18 collector rings t/ and f coils C and D, contact or collector rings cand d, contact-fingers c and d, contact segments c2, d2 and t,contact-finger t2 to the negative main T2. It'will thus be seen that theresistances 17 and 18 are connected in series with the coils `C and D,thus cutting down the amount ofcurrent which passes through said coilsand diminishing the effective magnetic attraction between said coils andtheir respective armatures, thus allowing the desired amount of slip inpassing from one coil to the next and eliminating the shock'or jar tothe apparatus. As vthe controller is moved into its ninth position andthe contact segment d3 leaves the contact-finger d, 'the circuit throughthe coil D is opened and the connection through the coil C is completedAin shunt to the resistance 17 when the contact segment c2 engages thecontact-finger e. In the ninth position the shunt around the resistance15 is again completed so that the speed of the motor is immediatelyreduced due to the strengthening of its field to that corresponding toposition four, that is, just enough or approximately enough tocompensate for the change in gear ratio in passing from the combinationof gears 374 and 38 to the combination of gears 35 and 36.

In passing through the tenth, eleventh twelfth and thirteenth positions,the various shunts around the sections of the resistance 15 which arecompleted through the contact segments 1", 2, 3 and 4c andcontact-fingers 1, 2, 3 and 4 are opened so that in the thirteenthposition the entire resistance" 15 is in series with the field 14 as inthe eighth position, of the controller, the magnet coil C remainingenergized throughout these succcssive operative positions of thecontroller. Y In passing from the thirteenth to the fourteenth positionthe same transition step of inserting the resistances 17 and 18 inseries with the magnet coils is repeated, this time the coils B and Cbeing connected in circuit simultaneously in series with saidresistances. In the fourteenth position the coil B is in circuit aloneand the speed of the motor is again reduced to that corresponding to thefourth and ninth positions of the controller. In passing from thepositions .fourteen to eighteen inclusive the speed of the motor isincreased step-by-step as before up to that corresponding to the eighthposition of the controller, the circuit through the magnet coil B heingmaintained throughout these successive operative positions.- The sametransition step of inserting resistances 17 and 18 as above described isrepeated in passing from the eighteenth to the nineteenth position ofthe controller, the speed ofthe motor being again reduced to the speedcorresponding to the fourth, ninth and fourteenth positions of thecontroller, by shunting the resistance l5. At this time coil A isconnected in circuit by the engagement of the contact segment al withthe contact-linger a. While passing through the remaining operativepositions of the controller the circuit through the magnet coil AA ismaintained and the speed of the motor is gradually increased byinserting the resistance l5 in the motor-held coil circuit..

It will thus be seen that with the mechanism above described a widerange oi spoed variation with a power output which is substantially thesame at low speeds as at high speeds is obtained by the use of a smallmotor the range of speed variation of which is comparatively limited.

The device just described constitutes the preferred embodiment of myinvention but I do not. care to be limited to the spccilic details ofconstruction herein shown and described as many changes andmodifications may be made b'y persons skilled in the art withoutdeparting from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent ot the UnitedStates. is-

1. In combination, a plurality of electromagnetic clutches in avariable-speed mechanism. a source of power variable in speed betweennarrow limits, and means for controlling the variation of the speed ofsaid source of power and for controlling the successive operation ofsaid clutches whereby a wide range of speed variation with a uniformacceleration is obtainable from said source of power.

2. In combination, a variable-speed mechanism comprising a plurality ofelectromagnetic clutches and transmittingr wheels having dilerent speedratios adapted to be thrown into operation successively by saidclutches. a source of power having a narrow range of speed variationoperatively connected with said clutches, and means for controlling thesaid variable-speed mechanism and said source of power so that a uniformacceleration through a wide range of speeds is'obtained.

In combination, a variable-speed mechanism comprising a plurality ofelectromagnetic clutches and transmitting wheels having different speedratios connected in operative relationship successively by saidclutches. a motor for driving said variable-speed mecllanism. and meansfor controlling the successive operation of said clutches and forvarying the speed of said motor between certain predetermined narrowlimits during the operation of each successive clutch whereby a uniformacceleration of said variable-speed mechanism through a wide range ofspeeds is obtained.

4. In combination, a variable-speed mechanism comprising a plurality ofelectromagnetic clutches and transmitting wheels having different speedratios connected in operative relationship successively by saidclutches. a source of power for driving said mechanism, and means forenergizing two successive clutches simultaneously and at the same timereducing the eli'ective attractive power 0f said clutches whereby acertain amount of slip is allowed while passing from the transmittingrwheels having;r a certain speed ratio to those having next higher orlower speed ratio.

In combination, a variable-speed mechanism comprising a plurality ofelectromagnetic clutches and transmitting wheels having different speedratios connected in operative relationship successively by saidclutches, a source of power connected with said mechanism, a resistance,and a controller for connecting two successive clutches in circuitsimultaneously and for inserting said resistance in circuit with saidclutches while passing from the operative positions of said controllercorresponding to one clutch to those corresponding to the nextsuccessive clutch.

G. In combination, a variable-speed mechanism comprising a plurality ofelectromagnetic clutches and transmitting wheels having different speedratios connected in operative relationship successively by saidclutches, a motor adapted to vary in speed between certain predeterminednarrow limits, a resistance, and a controller so constructed andarranged as to connect said clutches successively in circuit and whilecach of said clutches is in circuit to vary the speed of said motorbetween said predetermined limits and while passing through thetransition points between the operative positions corresponding to oneclutch to those corresponding to the next successive clutch to connectsaid clutches simultaneously in circuit with said resistance therebyreducing the elective magnetic attraction of said clutches to allow acertain amount ot' slip.

7. ln combination, a motor, an electrically operated variable speedmechanism driven by said motor, and a controller for alternatelyincreasing the speed ot the motor through a definite range and changingthe speed mechanism to its next faster position and vice versa.

S. In combination, a variable speed mechanism, a motor for driving saidmechanism, electrically operated means t'or changing the variable speedmechanism from one speed position to another, and means for varying thespeed of the motor through a definite range during each speed positionof the speed mechanism.

t). In combination, a variable speed mechanism, a motor for driving saidmechanism, means for operating said mechanism at one of its speeds,means for varying the speed of the motor, and means for shifting toanother speed of said mechanism and simultaneously returning the speedof said motor to its original value.

10. In combination, a variable speed mechanism, comprising a series ofclutches and transmission wheels having dierent speed ratios, a motorfordrving said mchanism, means for energizing one of said clutches,means for increasing the speed of 'said motor,` and means for energizinga second clutch having a higer speed ratio -and simultaneouslydenergizing the first clutch and decreasing the speed of said motor.

11. In combination, a variable speed mechanism, comprising a series ofelectro-magnetic clutches and transmission wheels having different speedratios, a motor for driving said mechanism, and a controlling switch forsaid motor and said clutches adapted to energize one of said clutches,then to insert 'resistance in the field of said motor, then to insertresistance in the circuit of said clutch and to energize through aresistance a second clutch having a higher speed ratio, and then todenergize the first clutch and to cut out the resistances from the iieldof motor and from the circuit of the second clutch.

12. The combination with a driving mechanism variable in speed betweennarrow limits, of a plurality of magnetic clutches in a variable speedmechanism, and means for gradually accelerating1 the driven members ofsaid clutches as they are successively operated.

13; The combination with a driving mechanism, having a variable speedwithin narrow limits, of a plurality of magnetic clutches, a pluralityof transmitting wheels having different speed ratios and thrown intooperation by said clutches, and means for gradually accelerating thespeed of the driven members of said clutches.

l-i. The combination with a motor, of means for varying the speedthereof, a plurality of magnetic clutches in a variable speed mechanism,and means for gradually accelerating the driven members of saidclutches.

15. The combination with a motor, of a plurality of speed-changing gearsfor connecting the same with the machinery to be driven, and means forinserting a resistance in the shunt field of the motor to increase thespeed thereof after each change of speed by said gears.

1G. The combination with a motor, of a plurality of speedchanging gears,and a plurality of magnetic clutches for connecting the same with themotor, and-means for increasing the 'speed of the motor above normalafter each change of speed of said gears.

1T. rlhe combination with a motor, of a plurality of magnetic clutches,a rheostat having a movable element,

means for controllingr said motor and said clutches in the desired wnyby the operation of said movable element.-

18. The combination with a motor, of n plurality of double magneticclutches, n rlleostnt having,r a movable element, said element in oneposition 'serving to cause the operation f said motor and in anotherposition to cause the operation of the several clutches.

19. The combination with a motor, of a plurality of magnetic clutches, arheostat and :r movable element therefor adapted to change the speed ofsaid motor after the operation of each of said clutches.

